Illuminating apparatus



C. H. WHEELER.

ILLUMINATING APPARATUS.

APPLICATION FILED IuLY 2,1921.

Patented Nov. 1, 1922.,

lowin Eatented `lhluiv. 7, T922.

NETE@ STATES mattez earner erraten.-

ClLYDE El. WHEELER, OE MIDLNE PARK, NEW JERSEY, ASSIGNOE TO WESTERN ELEC- TEIC COMPANY, INCORPORATED, OE NEW YORK, N. Y., A CORPORATION OE NEW veen. f

, TLLUMINATING APPARATUS.

To all whom it may concern.'

Be it known that ll, Cnvnn H. WHEELER, a citizen of the United States, residing at borough of Midland Park, in the county ot lBergen, State of New Jersey, have invented certain new and useful limprovements in lllluminating Apparatus, of which the folis a full, clear, concise, and exact'description. y

This invention relates to `illuminating apparatus and particularly to a method of propagating light in parallel rays without the use ot lenses.

lln using various types of optical apparatus it is usually desirable to obtain clearly defined imagesrand this result is practically always accomplished through the use of lenses. ln photography, and particularly in recorders used in connection with psychrometes and other apparatus requiring a great degree of accuracy, a perfect print is essential in order to obtain correct data as to the object on test. Such an instrument is described, for example, in an application ofy D. T. May, Serial No. 483,393, filled July 9, f 1921, which relates to a photographic re corder for determining humidity conditions and which' consists in the formation of an image of the top of the indicating column of a thermometer, the light rays'being passed throiigh the thermometer tube in such a manner as to be intercepted in that part of the tube occupied by the liquid and to pass through that part of the tube above the liquid. A sensitized paper placed adjacent -the tube andl on the side oppositev to the entrance of the rays will therefore show an image of that part of the tube through which the rays pass, and the lower end of this image will be the top of .the indicating column which indicates the temperature. This image may best'be recorded by vobtaining only parallel vertical rays of light since divergent light rays passing through the l wallswo-tthe thermometer are deflected over a widearea ot the photographic chart and tend to obscure the image.

llt is an object of this invention to provide a method of securing parallel rays of light without the use of lenses.

In accordance with'its object lthe invention contemplates producing parallellight raysy by the introduction of a sheet ot corrugated material inal rectangular tube through' which rays from a source of light must pass.

The corrugated sheet serves to establish a plurality ot barriers for divergent rays ot light toproduce parallelism inthe emitted rays, the degree of parallelism being dependent upon the proximity and length of the convolutions of the sheet. The invention 1s particularly suited for use in the abovementioned application of D. T. May, and its application to this device is considered in detail in the following description and in the accompanying drawing,

ln the drawing, Eig. 1 is a top sectional view showing the application of the invention to the transmission of light in a photographic recorder; Fig. 2 is an enlarged front sectional view of the apparatus in its pre-4 terred form; and Fig. 3-is a front section ot the rectangular tube containing the corrugated sheet.

Referring to the drawing, 1 represents the partition separating the chambers 2 and 3. A thermometer 4 having a bore 5 and surrounded by the metal Shielding tube 6 is mounted in front' of the partition,-the metal tube being attached to the partition byfa lighttight joint. rll`he tube 6 is provided with two openings extending longitudinally over the portion of the thermometer 'scale which it is desired to record. The opening 7 covers about 90 of the'v circumference ot the tube 6; and the opening 8 is a slit of .a width about equal to the diameter of the' bore 5. 'llhe partition 1 is provided with openings similar to and coinciding with thel slit 8 and on the opposite side ot the partition passes the photographic chart 9. The partition is also provided with an opening 10 before which is attached a transparent screen 11 provided on its edge with a scale identi-` on the inside wall out the compartment 2 and thence is' redected along the `line C to the screen 11.

the line E to a suitable 'reecting surface 15 y In order to obtain a correct reading with the above described apparatus, it is essential that the heiglit of the indicating column of the thermometer 4 be recorded with the greatest accuracy. In order that an accurate and well-definedfimage of the indicating column may be obtained it is necessary that the vertical raysl of light be approximately parallel; or in other words, the light from the source 12, passing along the line A within the shield 13 must rbe propagated in parallel rays in order that the rays which pass through the thermometer-at a given point may be fixed at` a corresponding point on the adjacent photographic chart. In accordance with the invention this is accomplished by` placing Within the sides of the shield 13 a strip of corrugated material, such as sheet metal, shown at 16. The corrugated sheet 16 serves to establish a. plurality of barriers for divergent rays of light and allows only parallel or substantially parallel rays to pass through. By decreasing thev size of the corrugations, and by increasing their length, fewer light rays will be allowed to pass through the passages and greater accuracy will be obtained. `The inventionv is not, however, limited to the use of corrugated material, it being possible .to employ a plurality of rectangular or circuf lar conduits disposed in the proper planes. The invention is shown more clearly in Fig.

2, vin which converging r'aysof light D are shown passing through the walls of the thermometer 4 at the top of the indicating column when the corrugated sheet `16 is notemployed. The resulting image upon the phoytographic chart 9 is a dense line extending over a length E suflicient to obscure the true height of the indicating column. When the corrugated strip 16 is placed within ythe shield 13, however, light rays D striking any portion of thecorrugations are deflected and do not reach the thermometer. Light rays F which pass through the passages provided by the corrugations strike the thermometer and photograph chart at substantially right angles thereto, thus producing an accurate image of the top of the indieating column of the thermometer.

In the rear chamber 3 of the recording apparatus the chart 9 passes from the spool 17 over the rollers 18 or other means employed to .keep it at against the partition, to the spool 19 which may be rotated in any suitable manner.

lVhat is claimed is:

1. The combination with a source of light of an object to be illuminated, a shield for said source of light conforming to the shape of'said object, and a sheet of corrugated material disposed in said shield and adapted to intercept divergent light rays.

2. The combination with a source of light of an object to be illuminated, a shield for said source of light, an outlet for the light rays conforming to the shape of said object,

and a sheet of corrugated material disposed `in said outlet and adapted to intercept divergent light rays.

In witness whereof, I hereunto subscribe my name this 29th day of June, A. D., 1921.

CLYDE H. WHEELER. 

